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Howlett" , dave.hansen@linux.intel.com, kirill.shutemov@linux.intel.com, Shakeel Butt , SeongJae Park , David Hildenbrand , Vlastimil Babka , Andrew Morton , Jens Axboe , Pavel Begunkov , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Ryan Roberts References: Content-Language: en-US From: Dave Hansen Autocrypt: addr=dave.hansen@intel.com; keydata= xsFNBE6HMP0BEADIMA3XYkQfF3dwHlj58Yjsc4E5y5G67cfbt8dvaUq2fx1lR0K9h1bOI6fC oAiUXvGAOxPDsB/P6UEOISPpLl5IuYsSwAeZGkdQ5g6m1xq7AlDJQZddhr/1DC/nMVa/2BoY 2UnKuZuSBu7lgOE193+7Uks3416N2hTkyKUSNkduyoZ9F5twiBhxPJwPtn/wnch6n5RsoXsb ygOEDxLEsSk/7eyFycjE+btUtAWZtx+HseyaGfqkZK0Z9bT1lsaHecmB203xShwCPT49Blxz VOab8668QpaEOdLGhtvrVYVK7x4skyT3nGWcgDCl5/Vp3TWA4K+IofwvXzX2ON/Mj7aQwf5W iC+3nWC7q0uxKwwsddJ0Nu+dpA/UORQWa1NiAftEoSpk5+nUUi0WE+5DRm0H+TXKBWMGNCFn c6+EKg5zQaa8KqymHcOrSXNPmzJuXvDQ8uj2J8XuzCZfK4uy1+YdIr0yyEMI7mdh4KX50LO1 pmowEqDh7dLShTOif/7UtQYrzYq9cPnjU2ZW4qd5Qz2joSGTG9eCXLz5PRe5SqHxv6ljk8mb ApNuY7bOXO/A7T2j5RwXIlcmssqIjBcxsRRoIbpCwWWGjkYjzYCjgsNFL6rt4OL11OUF37wL QcTl7fbCGv53KfKPdYD5hcbguLKi/aCccJK18ZwNjFhqr4MliQARAQABzUVEYXZpZCBDaHJp c3RvcGhlciBIYW5zZW4gKEludGVsIFdvcmsgQWRkcmVzcykgPGRhdmUuaGFuc2VuQGludGVs LmNvbT7CwXgEEwECACIFAlQ+9J0CGwMGCwkIBwMCBhUIAgkKCwQWAgMBAh4BAheAAAoJEGg1 lTBwyZKwLZUP/0dnbhDc229u2u6WtK1s1cSd9WsflGXGagkR6liJ4um3XCfYWDHvIdkHYC1t MNcVHFBwmQkawxsYvgO8kXT3SaFZe4ISfB4K4CL2qp4JO+nJdlFUbZI7cz/Td9z8nHjMcWYF IQuTsWOLs/LBMTs+ANumibtw6UkiGVD3dfHJAOPNApjVr+M0P/lVmTeP8w0uVcd2syiaU5jB aht9CYATn+ytFGWZnBEEQFnqcibIaOrmoBLu2b3fKJEd8Jp7NHDSIdrvrMjYynmc6sZKUqH2 I1qOevaa8jUg7wlLJAWGfIqnu85kkqrVOkbNbk4TPub7VOqA6qG5GCNEIv6ZY7HLYd/vAkVY E8Plzq/NwLAuOWxvGrOl7OPuwVeR4hBDfcrNb990MFPpjGgACzAZyjdmYoMu8j3/MAEW4P0z F5+EYJAOZ+z212y1pchNNauehORXgjrNKsZwxwKpPY9qb84E3O9KYpwfATsqOoQ6tTgr+1BR CCwP712H+E9U5HJ0iibN/CDZFVPL1bRerHziuwuQuvE0qWg0+0SChFe9oq0KAwEkVs6ZDMB2 P16MieEEQ6StQRlvy2YBv80L1TMl3T90Bo1UUn6ARXEpcbFE0/aORH/jEXcRteb+vuik5UGY 5TsyLYdPur3TXm7XDBdmmyQVJjnJKYK9AQxj95KlXLVO38lczsFNBFRjzmoBEACyAxbvUEhd GDGNg0JhDdezyTdN8C9BFsdxyTLnSH31NRiyp1QtuxvcqGZjb2trDVuCbIzRrgMZLVgo3upr MIOx1CXEgmn23Zhh0EpdVHM8IKx9Z7V0r+rrpRWFE8/wQZngKYVi49PGoZj50ZEifEJ5qn/H Nsp2+Y+bTUjDdgWMATg9DiFMyv8fvoqgNsNyrrZTnSgoLzdxr89FGHZCoSoAK8gfgFHuO54B lI8QOfPDG9WDPJ66HCodjTlBEr/Cwq6GruxS5i2Y33YVqxvFvDa1tUtl+iJ2SWKS9kCai2DR 3BwVONJEYSDQaven/EHMlY1q8Vln3lGPsS11vSUK3QcNJjmrgYxH5KsVsf6PNRj9mp8Z1kIG qjRx08+nnyStWC0gZH6NrYyS9rpqH3j+hA2WcI7De51L4Rv9pFwzp161mvtc6eC/GxaiUGuH BNAVP0PY0fqvIC68p3rLIAW3f97uv4ce2RSQ7LbsPsimOeCo/5vgS6YQsj83E+AipPr09Caj 0hloj+hFoqiticNpmsxdWKoOsV0PftcQvBCCYuhKbZV9s5hjt9qn8CE86A5g5KqDf83Fxqm/ vXKgHNFHE5zgXGZnrmaf6resQzbvJHO0Fb0CcIohzrpPaL3YepcLDoCCgElGMGQjdCcSQ+Ci FCRl0Bvyj1YZUql+ZkptgGjikQARAQABwsFfBBgBAgAJBQJUY85qAhsMAAoJEGg1lTBwyZKw l4IQAIKHs/9po4spZDFyfDjunimEhVHqlUt7ggR1Hsl/tkvTSze8pI1P6dGp2XW6AnH1iayn yRcoyT0ZJ+Zmm4xAH1zqKjWplzqdb/dO28qk0bPso8+1oPO8oDhLm1+tY+cOvufXkBTm+whm +AyNTjaCRt6aSMnA/QHVGSJ8grrTJCoACVNhnXg/R0g90g8iV8Q+IBZyDkG0tBThaDdw1B2l asInUTeb9EiVfL/Zjdg5VWiF9LL7iS+9hTeVdR09vThQ/DhVbCNxVk+DtyBHsjOKifrVsYep WpRGBIAu3bK8eXtyvrw1igWTNs2wazJ71+0z2jMzbclKAyRHKU9JdN6Hkkgr2nPb561yjcB8 sIq1pFXKyO+nKy6SZYxOvHxCcjk2fkw6UmPU6/j/nQlj2lfOAgNVKuDLothIxzi8pndB8Jju KktE5HJqUUMXePkAYIxEQ0mMc8Po7tuXdejgPMwgP7x65xtfEqI0RuzbUioFltsp1jUaRwQZ MTsCeQDdjpgHsj+P2ZDeEKCbma4m6Ez/YWs4+zDm1X8uZDkZcfQlD9NldbKDJEXLIjYWo1PH hYepSffIWPyvBMBTW2W5FRjJ4vLRrJSUoEfJuPQ3vW9Y73foyo/qFoURHO48AinGPZ7PC7TF vUaNOTjKedrqHkaOcqB185ahG2had0xnFsDPlx5y In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 06A3B4000A X-Stat-Signature: 1bo1sydz4umaytiq71hbjw1r55ob9r9d X-Rspam-User: X-HE-Tag: 1736889216-304636 X-HE-Meta: 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 rpeKeBD2 ofZzz2BSdDDHl60jREBo7nSl/YhnTm9aWG/MKkVExGn80RY53f7g46fEeNd4Z1guTE7UAZ6iK2Mi0FcaD7LnVN6Fxw/8GRLrrmNXzgFgVRai39FJoIWjkauJcDRdKTg7E4MqWuKjISSSFTmLWxDUyWZg/oRAAx01Hf1L0uBajXclEC5uFCiBc6/D8lyOExl9gNvAxDZku7EtLhinsOBeYkRD7FK7IUFmpxzLpIYpeOee28p/IEsThwTtXTvX8pSH5dkVZ24GlxLhzoTDxK9iNiMMFTbKPO0c4NXIi1gsfpy0361vKf1EVLaNr9f1tVt/Tx4F8 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 1/14/25 12:41, Lorenzo Stoakes wrote: ... > However, MADV_HWPOISON, MADV_SOFT_OFFLINE seems fundamentally broken for tagged > addresses: > > #ifdef CONFIG_MEMORY_FAILURE > if (behavior == MADV_HWPOISON || behavior == MADV_SOFT_OFFLINE) > return madvise_inject_error(behavior, start, start + len_in); > #endif > > ^ this is invoked before untagged_addr_remote() is called (as no mmap lock is > acquired) and so no attempt at untagging happens at all...! Except this call path: madvise_inject_error() -> get_user_pages_fast() -> gup_fast_fallback() does its own untagging: start = untagged_addr(start) & PAGE_MASK; It might also have some funky behavior if start+len_in overflows. But, just as in the other case, it's invalid to begin with so I think userspace kinda gets to keep the pieces. But I do 100% agree that this is non-obvious. In a perfect world, tagged addresses would get untagged at the user/kernel boundary in _one_ choke point. But the world is hard and that would make things too easy and then we wouldn't get paid the big bucks. ;) To clarify things, I don't think it'd be the worst thing to just move the madvise_inject_error() down and have that case acquire mmap_read_lock(). Sure, it's not required, but it's basically debugging code and I can't imagine it's avoiding the lock for performance reasons.